1. Field of the Invention
This invention relates to an apparatus for breaking a mass of substantially coherent tobacco containing solid cryogen such as carbon dioxide into smaller particles to facilitate transfer of such processed tobacco to subsequent processing equipment.
2. Description of the Prior Art
A process and apparatus for expanding tobacco by impregnation with a liquid cryogen, in particular, liquid carbon dioxide is described in patent applications U.S. Ser. No. 441,767 filed by Roger Z. de la Burde and Patrick E. Aument on Feb. 12, 1974 and U.S. Ser. No. 822,793, filed by Larry M. Sykes and Ray G. Snow on Aug. 8, 1977, both applications being assigned to the same asignee as is the present invention. As described in these applications, after the tobacco is thoroughly impregnated the excess liquid carbon dioxide is removed from the chamber in which the tobacco is processed and the liquid carbon dioxide is converted therein to solid carbon dioxide. The tobacco containing the solid carbon dioxide may be removed from the processing chamber and subjected to conditions of temperature and pressure, preferably by rapid heating at atmospheric pressure, to vaporize the solid carbon dioxide and thereby effect expansion.
In U.S. Pat. No. 4,165,618 to Lewis Tyree, Jr., issued on Aug. 28, 1979, apparatus is provided for removing a treated tobacco product containing solid carbon dioxide from a processing chamber by gravity through a hinged bottom door that allows the processed tobacco product to fall onto a conveyor or the like. The conveyor then transports the processed product to stations for further desired processing in a production-like fashion. One problem with discharging such processed tobacco to a moving conveyor occurs with the size of the processed product. In production, it is not uncommon to impregnate a charge of tobacco weighing up to 750 pounds. The charge of tobacco may gain an additional 10% of its weight after impregnation with the liquid carbon dioxide. Upon conversion to solid, the liquid carbon dioxide is caused to freeze. Since the liquid carbon dioxide is interspersed throughout the charge of tobacco there is a tendency upon solidification for the charge to coagulate into a substantially coherent mass or into several relatively large clumps of tobacco containing the solid carbon dioxide. Such a large mass or clumps of tobacco cannot be readily conveyed or transported to subsequent processing stations.
Before being transferred to a moving conveyor or the like it is therefore desirable, in particular with a large charge of tobacco, to break such a mass down into smaller particle sizes. Furthermore, it is desirable to break the mass down preferably into particles that have a maximum size to facilitate a controlled and gradual transfer to a moving conveyor or other processing equipment for subsequent processing of the tobacco. For example, for substantially even distribution to a moving conveyor, the processed tobacco is sometimes passed into and through a vibrating container. Clumps of tobacco too large for the infeed throat of the vibrating container would cause the throat to become clogged thereby backing-up the transfer process and ultimately requiring a stoppage of the production line.